Security Intro

Question 1

What are the four principles of security?

Answer 1

• Confidentiality
• Authentication
• Integrity
• Availability

Question 2

What is the “Confidentiality” principle of security?

Answer 2

Only sender and intended receiver should understand the message contents

Question 3

What is the “Authentication” principle of security?

Answer 3

Sender and receiver want to confirm each other’s identity

Question 4

What is the “Integrity” principle of security?

Answer 4

Sender and receiver want to ensure that the message is not altered without detection

Question 5

What is the “Availability” principle of security?

Answer 5

Services must be accessible and available to users

Question 6

What are the four actions an intruder can take?

Answer 6

• Eavesdrop: Intercept message
• Impersonation: Can fake source address in packet
• Hijacking: Take over ongoing connection by removing sender or receiver, inserting themselves in place
• Denial of Service: prevent service from being used by others

Question 7

What does an encryption algorithm comprise of?

Answer 7

• A method for encrypting the data
• A method for decrypting the data
• A secret key used in the decryption / encryption method

Question 8

What are three methods for breaking an encryption scheme?

Answer 8

• Ciphertext-only attack
• Known-plaintext attack
• Chosen-plaintext attack

Question 9

Describe the Ciphertext-only attack

Answer 9

• Intruder has ciphertext but not plaintext
• Option 1: brute force, search through all keys
• Option 2: statistical analysis (look for patterns)

Question 10

Describe the Known-Plaintext Attack

Answer 10

Intruder has some ciphertext with its plaintext, wants to break other ciphertexts

Question 11

Describe the Chosen-Plaintext Attack

Answer 11

Intruder has the ability to encrypt any plaintext but doesn’t have the key for decryption